This invention refers to an apparatus and methods for releasably securing a freight container of standard type (ISO standard) to a loading platform and/or to another container within a stack of a multiplicity of such freight containers.
As is well known in the art, standard freight containers of the type described have at each corner fitting in which there is an elongate orifice in the horizontal face, the orifice opening into a recess within the corner fitiing.
The state of the art is shown in U.S. Pat. No. 3,894,493 which teaches "A selectively operable stacker key locking device adapted to secure cargo containers either in vertical or horizontal adjacent stacked relation or to secure a container to a base support. The locking device includes a base member, a neck member and an elongated shank member to which a crosshead container locking member is connected. Internal means are provided to securely lock the shank member to the neck member thereby securing the container while several alternative means may be provided to secure the base member of the locking device to either another container or to a base support without interfering with the locking capability or functioning of the container locking features thereby providing independent alternative means to secure the locking device." The alternative device to secure the locking device can be a simple twist lock as shown described in said patent.
A problem which arises in the use of said type locks is that they are very subject to corrosion since they are often exposed to the elements in conventional use. This corrosion is very deleterious because it impedes movement between the lugs located on the shank member and the neck member thereof to lock these two pieces together. It can cause the cone portion thereof to be affixed in a locked position which prevents actuation of the lock by the key means.
Some conventional locking devices used in the art have a rotatable cone mounted on a shaft which is capable of being inserted in a ISO corner fitting orifice, with the cone being rotated thereafter to prevent the locking device from being removed from the corner fitting. In these devices when they are in a locked position the underside of the cone abuts the inner wall of the corner fitting. Here, too, corrosion can be very deleterious since no provision is made in such devices to urge the underside of the cone away from the innerside wall of the corner fitting to prevent it from being jammed up by the effects of corrosion.
The art has long sought a container interlock which is economic to produce, easily actuable and which can overcome the effect of corrosion buildup on interfaces between the lock surface and the container surface which can be safely installed on the containers and easily removed therefrom.